Someone who is very strange. Primarily heard in UK. Everyone could tell he was a queer fish as soon as he walked into the party with his mismatched clothing.
an ˌodd/a ˌqueer ˈfish
(old-fashioned, British English) a strange person: He’s an odd fish. He’s got a lot of very strange ideas.
queer fish
n. a strange person; an aloof person. She’s a bit odd. Sort of a queer fish.